1. Field of the Invention
The present invention relates to an active-clamp flyback power converter, and, more specifically, the present invention relates to a control circuit of the active-clamp flyback power converter.
2. Description of the Related Art
The traditional active-clamp circuit can only achieve zero-voltage switching at particular load condition. Besides, its high circulated current during light-load condition causes higher power loss problem. The related prior arts can be found in “Clamped Continuous Flyback Power Converter”, U.S. Pat. No. 5,570,278; “Offset Resonance Zero Voltage Switching Flyback Converter” U.S. Pat. No. 6,069,803 and “Active-clamp Circuit for Quasi-resonant Flyback Power Converter”, U.S. patent application 20110305048.